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  1. #1
    Join Date
    May 2004
    BA [ARG]

    Unanswered: Does adding a new LUN to a multi-instance cluster affect the rest of the instances?

    I'm looking into building a shared SQL environment using two servers as a 2-node Active/Active cluster, and attached to a NetApp SAN.
    I'm planning on installing SQL Server 2008 R2 on Windows Server 2008 R2 64-bit.

    My question is the following:
    Let's suppose I have 2 SQL Server instances per server/node (4 in total). If I want to add a third by adding new LUNs to the cluster... do I have to bring down the rest of the SQL Server instances on the same node?
    Or is that something that can be done on the fly without affecting the rest of the instances? (I know it affects SSIS)

    Thanks in advance for any tip!

  2. #2
    Join Date
    Aug 2006
    San Francisco, CA
    From my experience, adding a new LUN to a cluster does not require a reboot of the server nor should it interrupt existing SQL Server instance. Once windows has discovered the new LUN and if you want to add it to an existing cluster group (existing SQL Server install) it will require a restart of that particular cluster group. If you are creating a new cluster group or SQL Server installation it should not affect the other instances.

    That being said, I would still highly suggest following these tips:
    1. Do the work during off hours
    Adding new hardware to a server is always an unknown and could force a server boot
    2. Make sure all the instance of SQL Server on the cluster is the same version.
    I ran into an issue were I had a 2 node cluster (active\active) both instances SQL Server 2005 64-bit SP2 and we added another very small instance (active, active\active). Another DBA installed SP3 on the new instance which caused issues until we restarted both nodes to clear the install files. So you might have to restart if you are doing a new install.

    Also have a look at this article:
    How to: Add Dependencies to a SQL Server Resource

    Good luck! I hope this helped.
    Last edited by Reghardt; 05-19-10 at 14:42. Reason: Adding MS Link

  3. #3
    Join Date
    Feb 2004
    In front of the computer
    Provided Answers: 54
    The answer depends more on the NetApp configuration than any other factor. In general, if your SAN configuration allows you to mount a new LUN and make it visible to the Operating System, then you should have no problems getting the Windows Cluster to use the new LUN and make it available to SQL Server.

    In my experience, NetApp seems very fragile compared to other SAN setups in this respect.

    In theory, theory and practice are identical. In practice, theory and practice are unrelated.

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